It has become too common that an armed individual enters a school or other building and threatens or injures occupants. The individual is often an outsider, as in the case of the Amish school incident, or a school student, as in the Columbine killings. This problem occurs also in offices, banks, and many other public or semi-public buildings. Public buildings such as courthouses have installed metal detectors and posted guards. Many larger schools have hired guards or actual police. These security measures have been somewhat effective, but those who are sufficiently motivated or deranged tend to find ways to circumvent the gatekeeping protections.
Once an incident has begun, the security personnel or police that arrive are unaware of the details of the situation within the facility. This lack of current information hinders resolution, since the police or security may not know the number of intruders, type and number of weapons, and the actual conditions. Attempts to negotiate with the intruder and bargain a solution are critical. This can only be helpful if a communication link is accessible. When the threat occurs in a school building, direct communication with a specific room is often not available, and broadcasting negotiations to multiple rooms is likely to add panic to the situation.